A fuel-injection valve with electromagnetic actuation is described in published German Patent Application No. 40 13 832 A1. In the fuel-injection valve described therein, a connecting ring, formed from a non-magnetic material having a high specific electrical resistance, is securely and hermetically joined to an internal pole and to a valve sleeve of the fuel-injection valve. This ensures that no fuel can reach a solenoid situated between the internal pole and the valve sleeve; i.e., a solenoid surrounding the internal pole and being surrounded itself by the valve sleeve. Because the connecting ring is made of a non-magnetic material, its effect on the magnetic field is quite negligible. The connecting ring prevents a magnetic short-circuit between the internal pole and the valve sleeve and avoids additional eddy losses.
The fitting of the connecting ring, however, is a relatively cost-intensive process. For example, to manufacture the magnet body out of an internal pole, a valve sleeve and a connecting ring, an inner and outer soldering ring are still needed to be able to produce permanent, hermetically sealed connections. Thus, for example, five individual component parts are needed to manufacture the magnet body. The individual structural elements, i.e., the internal pole, valve sleeve, and connecting ring, must be manufactured very precisely and assembled together before the jointing operation. Manufacturing the individual, highly precise structural elements, and assembling the structural elements, while achieving hermetic and secure connections, entail expensive processes.